Sight and Song

Percy Jackson never cried, never cooed, and never spoke. To his mother, he was a silent miracle-a child who seemed to feel the world rather than respond to it. But beneath the quiet exterior lay something far more profound: an understanding of things no child should know, and a voice that refused to be spoken aloud.
or
Percy Jackson is a Seer, a Siren, and a Child between the two faces of the Sea. Because he is a Seer, he is part of the Sun. Because he is a Siren, and Siren's always sing, he is part of the Sun. But extra attention from other Beings is always tragic, so the Sea tries to hide their Pearl from Them.
Which includes the Sun, and the Moon, and the Sky, and the Owl, and the Messenger, and the Beauty, and the War, and the Wine, and the Forge, and everyone else in the Divine Realm.